1. Field of the Invention
This invention generally relates to surgical drill guides and more specifically to an improved surgical drill guide that provides positive position control of a drill guide tube, particularly during arthroscopic surgical procedures.
2. Description of Related Art
Surgical drill guides are well known in the art. They are very useful in enabling a surgeon to locate a drill guide tube with accuracy relative to adjacent anatomical structures. Generally these drill guides include a housing with a passage for a guide tube that extends along a guide tube axis. A handle portion of the surgical drill guide carries both the housing and a probe with a target end. The probe positions the target end at a location on a bone that intersects the guide tube axis. Generally some mechanism associated with the housing enables the guide tube to move along the axis into contact with the bone so the bone lies on a line between the distal end of the guide tube and the target. Once positioned, a guide is advanced through the guide tube and driven into the bone. Then the guide tube is removed from the guide and the surgical drill guide is removed from the patient. The guidewire enables the surgeon to position a drill bit at the bone and perform any necessary drilling operation.
It is important that the guide tube remain fixed against the bone while the guidewire is being inserted. That is, once the guide tube is in position, some mechanism must prevent inadvertent proximal displacement of the guide tube. However, that mechanism must readily allow the guide tube to be removed once the guidewire is affixed to the bone. The following patents disclose number of examples of such mechanisms:
U.S. Pat. No. 4,920,958 (1990) Walt et al. PA1 U.S. Pat. No. 5,154,712 (1992) Trott et al. PA1 U.S. Pat. No. 5,163,940 (1992) Bourque PA1 U.S. Pat. No. 5,458,602 (1995) Goble et al. PA1 U.S. Pat. No. 5,613,971 (1997) Lower et al.
U.S. Pat. No. 4,920,958 discloses one embodiment of a drill guide assembly with a cannular elongated wire guide for directing a guide wire. The wire guide can slide longitudinally along its axis. A locking spring prevents movement of the wire guide proximally after it is positioned. The locking spring produces sufficient sliding friction between the spring and the wire guide to prevent inadvertent wire guide motion. With this system a surgeon uses two hands to move the wire guide without interference from the locking spring or uses sufficient force to overcome the sliding friction that produces the original locking action.
U.S. Pat. No. 5,154,720 discloses a drill guide in which a cylindrical guide tube is secured to a handle so that it may not be easily longitudinally moved in either direction without the user engaging a thumb activated locking mechanism. The cylindrical guide tube passes through a conically tapered cylindrical bore within the drill guide. A similarly tapered split collet is interposed concentrically between the exterior of the cylindrical guide tube and the interior of the bore. This collet has a plurality of longitudinally extending lobes which are sufficiently resilient so that movement of the collet to its proximal-most position causes the lobes to squeeze inwardly against the cylindrical guide tube. Friction engagement between the collet lobes and the guide tube prevents the guide tube from moving until the collet is moved distally to release pressure on the lobes. The collet is normally biased proximally by a leaf spring attached to the drill guide handle. A thumb activated lever moves the leaf spring distally to release pressure on the lobes and unlock the cylindrical guide tube.
The locking function disclosed in U.S. Pat. No. 5,154,720 seems entirely dependent upon the capability of the mechanism to exert sufficient sliding friction to prevent unwanted motion of the guide tube. In addition, it appears that a surgeon must use two hands to move the wire guide without interference or must apply a sufficient force to the guide tube to overcome the sliding friction that produces the original locking action.
U.S. Pat. No. 5,163,940 discloses a surgical drill guide for tibia. This surgical drill guide includes an arcuate support beam having a drill guide locator and locator probe. The drill guide locator holds a cannulated drill sleeve or tube by means of a sleeve locking mechanism. The sleeve locking mechanism comprises a cam surface trigger lock with an inclined surface and biased plunger member. When the sleeve locking mechanism is operated, a latch housing manually moves between a locked position and an unlocked position. In a locked position the cam surface engages a plunger pin and in turn forces the pin housing against the guide sleeve or tube. The surgical drill guide also includes a plunger that prevents the sleeve from being dislodged or falling out when the device is moved or utilized while the locking mechanism is unlocked. In this reference locking the guide tube also relies upon sliding friction. Moreover, a surgeon must manipulate the guide tube directly to advance the guide tube to a final position.
U.S. Pat. No. 5,458,602 also discloses a surgical drill guide with a mechanism for advancing the guide tube and locking the guide tube in place. The advancing mechanism comprises a single-fold leaf spring and gripper plate through which the guide tube passes. A surgeon can index the guide tube or sleeve into position by depressing a trigger as by moving a thumb off a locking lever and onto an adjacent trigger. Depressing the trigger causes its cam portion to engage the gripper plate so that it engages the outer surface of the guide tube and advances the tube distally. Upon releasing pressure from the trigger, the leaf spring urges the gripper plate proximally and locks the guide sleeve in place. To remove the drill sleeve, a surgeon engages a lock release gripper to compress the leaf spring and release the edge of the plate from the drill sleeve.
U.S. Pat. No. 5,613,971 discloses another surgical drill guide in which the guide sleeve includes teeth along a portion of its circumference. In an operating position, the teeth face a double-toothed pawl. As a surgeon pushes the guide tube distally, the guide tube passes the pawl that is spring loaded so that upon release of the guide tube the pawl locks against a tooth and prevents any proximal displacement of the tube. The surgeon unlocks the guide tube by twisting the guide tube so that the teeth are angularly displaced from the pawl whereupon the guide tube can be removed as the pawl slides over a smooth surface on the guide tube.
With the exception of U.S. Pat. No. 5,613,971, the foregoing prior art generally discloses mechanisms for preventing inadvertent proximal motion of a guide tube that depend upon sliding friction forces to lock the guide tube. With the exception of U.S. Pat. No. 5,458,602 each of the surgical drill guides in the aforementioned prior art requires a surgeon to manipulate the guide tube directly in order to advance the guide tube to a final position against a bone. While the use of a pawl for engaging teeth on a guide tube is disclosed in U.S. Pat. No. 5,613,971, that specific embodiment merely requires a surgeon to rotate the guide tube to defeat the lock. It appears possible to produce such a rotation inadvertently so that the ability of the mechanism to hold the guide tube against the bone becomes unreliable.